Braille cell and display comprising a plurality of braille cells, as well as a method for controlling a plurality of pins of a braille cell

ABSTRACT

A Braille cell having a pressure-exerting member in the form of a bar or leaf spring, of which one end can be displaced with the aid of a first displacement mechanism in a direction that is perpendicular to a longitudinal direction. One end of the pressure-exerting member is configured for placement in either a first or second position. In the first position, the pressure-exerting member does not place touch pins in a high position, while in the second position, the pressure-exerting member does place the touch pins in a high position. A second displacement mechanism is configured to displace the end of the pressure-exerting member, after the end has been disposed in one of the first or second positions, in the longitudinal direction, in such a manner that a touch pin is placed or is not placed in the high position. This allows a touch pin to be fixed in the correct position with respect to the touch surface of the touch board in a very simple manner.

The invention relates to a braille cell comprising a frame, a touchboard and a plurality of touch pins, each touch pin being enclosed in acavity in the touch board in such a manner that it can be displaced froma low position, in which the touch pin does not project above the touchsurface of the touch board, to a high position, in which the touch pinprojects above the touch board by a specific, desired length, and inwhich frame there is arranged a displacement member, which displacementmember can be moved into a desired position under the influence ofdisplacement means, with the result that, depending on the position ofthe displacement member, a touch pin which is enclosed in a cavity in atouch board may or may not be moved into the high position, in which itprojects above the surface of the touch board, as well as to a methodfor controlling a plurality of touch pins of a braille cell.

Braille cells of the type described above are known, inter alia, fromAmerican U.S. Pat. No. 4,283,178. A braille cell of this kind can beused to make a braille symbol which can be detected by the visuallyhandicapped using their fingers. By placing a plurality of braille cellsin succession, it is possible to form a number of words. By usingbraille cells of this kind in combination with, for example, a computerterminal, it is possible for the visually handicapped to perceive theinformation from the computer.

However, the known braille cells have a number of drawbacks. The braillecells, which are provided with many piezoelectric bending elements, areexpensive to produce. Moreover, it is important for the braille symbolsto be of a fixed size, so that the correct meaning can be worked out bythe visually handicapped. Also, the structure and shape of the braillecells known to date mean that it is only possible to form a singlereading line, so that often it is only possible to display parts ofsentences, and not complete passages of text. Moreover, braille cells ofthis kind have to be cleaned regularly, since dirt from the fingerspenetrates into and around the pins in the small holes in which the pinsmove up and down. Since there are numerous electronic components in thevicinity of this pin, cleaning the braille cells is a verylabour-intensive operation. Moreover, the lengths of the various touchpins in a braille cell are different, with the result that a pluralityof different components are required when assembling the braille cells,resulting in extra costs.

The object of the invention is to provide a braille cell which can beproduced at low cost and is formed in such a way that a large number ofbraille characters can be placed next to and above one another, so thata braille reading board composed of a plurality of lines can beassembled, and preferably a display.

This object is achieved with a braille cell of the type described in thepreamble by the fact that the pressure-exerting member is a member, forexample in the form of a bar or leaf spring, of which one end can bedisplaced, with the aid of first displacement means, in a directionperpendicular to the longitudinal direction, it then being possible toplace the one end of the bar-like member in a first or a secondposition, in which case in one of the two positions thepressure-exerting member cannot place the specific touch pin in the highposition and in the other position the pressure-exerting member canplace the specific touch pin in the high position, and it being possiblefor second displacement means to displace the end of thepressure-exerting member, after the end has adopted one of the twopossible positions, in the longitudinal direction, in such a manner thata touch pin is placed or is not placed in the high position. Thismeasure allows a touch pin to be fixed in the correct position withrespect to the touch surface of the touch board in a very simple manner.

In a preferred embodiment of the braille cell according to theinvention, the first displacement means comprise a plurality of firstdisplacement members, it being possible for each first displacementmember to displace the end of a plurality of pressure-exerting members,and a retention member is arranged in the frame close to each touch pin,which retention member serves to hold the end of the pressure-exertingmember, after the latter has been displaced over a specific distance inthe longitudinal direction with the aid of the second displacementmeans, in the desired first or second position. This measure makes itpossible to produce a very compact braille cell.

In one embodiment of the Braille cell described above, each firstdisplacement member may be configured to be displaceable by eitherpiezoelectricity or magnetic forces. Also, the second displacement meansmay be a camshaft.

In another possible preferred embodiment according to the invention, aplurality of braille cells are combined to form a display in such amanner that the display comprises a touch board, in which a plurality ofgroups of touch pins are arranged, it being possible for each group oftouch pins to form a braille symbol.

This measure allows all the pressure-exerting members of the variousbraille symbols to be placed in the desired position very quickly andthen allows all the braille symbols to be formed simultaneously and madetangible to a visually handicapped person.

Preferably, the method for controlling a plurality of touch pins of abraille cell is such that the end of a first pressure-exerting member isplaced in a desired first position or a second position with the aid offirst displacement means, so that the end of a first pressure-exertingmember can interact with a member, preferably a wedge-shaped member, andsuch that the first pressure-exerting member is then displaced in thelongitudinal direction, with the aid of second displacement means, overa distance which is such that the end is placed on one side or the otherof the wedge-shaped member, depending on the first or the secondposition, after which the first pressure-exerting member is displacedfurther in the longitudinal direction, so that the end of the firstpressure-exerting member, depending on the location with respect to thewedge, is able or is unable to displace a touch pin and retain it in adesired position. A device which operates in accordance with the methodaccording to the invention has the advantage that the first displacementmeans can control a plurality of pressure-exerting members; as a result,it is also possible to produce a braille cell, as well as a displaywhich is composed of a plurality of braille cells next to one another,more cheaply and in a more compact form.

Adding the following method to this method, namely in that after a firstpressure-exerting member has been placed in a desired position with theaid of the first displacement means, the same first displacement meansare then used to place a second pressure-exerting member in a desiredfirst position or a second position, so that the end of the secondpressure-exerting member can interact with a second member, preferably awedge-shaped member, in that the second pressure-exerting member is thendisplaced in the longitudinal direction, with the aid of seconddisplacement means, over a distance which is such that the end of thesecond pressure-exerting member is placed on one side or the other ofthe second wedge-shaped member, depending on the first or the secondposition, after which the second pressure-exerting member is displacedfurther in the longitudinal direction, so that the end of thepressure-exerting member, depending on the location with respect to thewedge, is able or is unable to displace a touch pin which is not thetouch pin displaced by the first pressure-exerting member and can retainthis other touch pin in a desired position, allows such a deviceaccording to the invention to be made even more inexpensive. The compactdesign means that it is possible in a simple manner to construct abraille reading board comprising a plurality of lines.

The invention will be explained in more detail with reference to thedrawing, in which:

FIG. 1 shows a diagrammatic illustration, in side view, of two braillecells according to the invention;

FIG. 2 shows a longitudinal view of a braille cell in accordance withFIG. 1;

FIG. 3 shows a perspective view of a braille cell in accordance withFIGS. 1 and 2;

FIGS. 4A-D show successive steps in making a braille symbol readable ina braille cell in accordance with FIG. 1;

FIG. 5 shows a diagrammatic side view of another possible braille cellaccording to the invention;

FIG. 6 shows a longitudinal view of a braille cell in accordance withFIG. 5.

FIG. 1 diagrammatically shows two braille cells 1. Each braille cell 1comprises a frame 2 with a touch board 3. The braille cell 1 compriseseight touch pins 4, which can be displaced in the longitudinaldirection, are accommodated in openings or cavities 5 partially in theframe 2 and partially in the touch board 3, and can be slid up and downbetween a retracted, low position, in which the pins 4 do not projectabove the top surface of the touch board 3, and an extended, or high,position, in which the pins 4 project above the top surface of the touchboard 3, in such a manner that a user can feel the pin 4 in questionwhen it has been placed in the high position. The small pins 4 arearranged in two rows of four pins 4 per braille cell 1. In this way, sixof the eight pins can be used to form braille symbols. The remaining twopins 4 can be used for extra information, for example upper-caseletters, an accent, figures. The pins 4 each comprise a cylindrical body6 on which there is arranged a rounded, narrow end 7, the diameter ofthe thin end 7 being less than the diameter of the cylindrical body 6,so that a shoulder 8 is produced. The openings 5 are correspondinglydesigned with a cylindrical narrowing 9 in the touch board 3. When a pin4 is pushed upwards, the shoulder 8 strikes the underside of thecylindrical narrowing 9, so that the pin 4 cannot slide out of the frame2. Due to the fact that the end 7 is longer than the cylindricalnarrowing 9, the pin, if placed in the high position, projects above thetop surface of the touch board 3, so that it can be felt by the touch ofa user.

A pressure-exerting member or leaf spring 10 is arranged in line witheach of the pins 4. That end of each pair of leaf springs 10 which isremote from the pins 4 is attached in the region of an end in a slidablepart, or sliding part 11. The sliding part 11 can be displaced in thelongitudinal direction of the leaf springs 10. A pair of leaf springs 10is attached in each sliding part. Both the pins 4 and the leaf springs10 are arranged in pairs. A displacement member or bending element 12 isplaced between the two leaf springs 10 of each pair of leaf springs,which bending element can bend, by means of a control signal, in a planewhich is essentially transverse to the longitudinal direction of theleaf springs 10. This bending element 12 is a small elongate bar whichis fixed at one end 13 with respect to the frame 2, while the other,free end 14 can bend backwards and forwards and is situated between fourpairs of leaf springs which are arranged around the bending element insuch a way that four leaf springs 10 are disposed on either side of theend of the bending element 12, which leaf springs can bend in a planewhich is essentially perpendicular to the bending element 12. In thisexemplary embodiment, the bending element is designed as a piezoelectricbending element, which is provided on both sides with a layer ofpiezoelectric material 15, to which an electric power supply isconnected. If a potential is applied to one of the layers 15, thepiezoelectric material contracts, so that as a result the bendingelement 12 bends. When the potential returns to the original level, therelevant layer 15 is rest red to its original shape and the bendingelement 12 will be straight again. Each leaf spring 10 is provided witha small projection 16.which faces towards the bending element. Thedimensions and position of the projection 16 are such that when the leafspring 10 is situated in the at-rest position the projection lies nextto the bending element 12, while when the leaf spring 10 is extended theprojection 16 is no longer situated next to the bending element 12.

Between each leaf spring 10 and each pin 4, there is a wedge-shaped bodyor wedge 17, with a sloping side 18 and a straight side 19 which runsessentially parallel to the leaf springs 10. For each pair of leafsprings 10, a short wedge 20 is laced opposite the end of one leafspring 10, while a long wedge 21 is placed opposite the end of the otherleaf spring 10, in such a manner that the straight side 19 of the longwedge 21 and the straight side 19 of the short wedge 20 face oneanother. An intermediate piece 22 is placed between the short wedge 20and the long wedge 21. At the end 23 which faces towards the leafsprings, this intermediate piece 22 is bevelled slightly. A gap 24,which is slightly wider than the thickness of the leaf springs 10, isleft clear between the intermediate piece 22 and the short wedge 20 andlong wedge 21. These gaps 24 each lie in line with the associated leafspring 10. As a result, each leaf spring 10 can be pressed or slidagainst the underside of the corresponding pin 4, via the gap 24.

The braille cell 1 works as follows. In the at-rest position, on, allthe pins 4 are retracted, so that they do not project above the topsurface 3 and thus cannot be detected by touch. The leaf springs 10 arelikewise in the at-rest position in which the projections 16 lie next tothe bending element 12. If a specific symbol, for example a specificletter, is to be displayed in braille with the aid of the braille cell1, a number of control signals are generated for activating the slidingparts 11 and the bending elements 12. The pairs of adjacent leaf springs10 are activated one by one. In the pair of leaf springs 10 which isactivated first, initially the leaf spring 10 whose free end ispositioned opposite the long wedge 21 is activated. If it is necessaryto display a braille symbol where the associated pin 4 has to remainwithdrawn beneath the surface of the touch board 3, a potential isapplied to that piezoelectric layer 15 of the bending element 12 whichfaces towards the leaf spring 10 in question, this potential being ofsuch a magnitude that the bending element bends towards the leaf spring10 and, with the aid of the projection 16, bends the leaf spring 10 tothe side. This situation is illustrated in FIG. 4A. However, it it isnecessary to display a braille symbol where the associated pin 4 has tobe extended above the top surface of the touch board 3, the bendingelement 12 is not bent, so that the leaf spring 10 likewise does notbend. The sliding part 11 is then slid in the direction of the wedge 21long until it reaches a first position in which the end of the leafspring 10 has moved past the end of the wedge 21 long but the end of theother leaf spring 10 has not yet moved past the end of the short wedge20. If the leaf spring 10 has been bent by the bending element 12, theleaf spring 10 can no longer bend back when the bending member isreturned to the unbent position, since the end of the spring 10 isresting against the sloping face of the wedge 21 long. The leaf spring10 thus remains in the selected position even when the bending element12 bends back again. This situation is illustrated in FIG. 4B. The otherleaf spring 10 is now placed in the desired position. If the associatedpin 4 needs to be extended in order to be able to display the desiredbraille symbol, the leaf spring 10 has to continue to move straight onin the direction of the gap 24. However, if the pin 4 is not to beextended, the piezoelectric bending element 12 is bent so that it pushesthe leaf spring 10 to the side. After the leaf spring 10 has been placedin the selected position, the sliding part 11 is moved further upwardsuntil the end of the leaf spring 10 moves past the end of the shortwedge 20. The selected position of this leaf spring 10 is now fixed bythe short wedge 20 This situation is illustrated in FIG. 4C. Theremaining pairs of leaf springs 10 are now placed in a selected positionin a corresponding manner. When all the leaf springs of the braille cellhave been placed in a selected position, the sliding parts 11 aresimultaneously slid further in the direction of the top surface 3, theleaf springs 10 which have not been bent out of the straight positionbeing pushed through the associated gap 24 and against the underside ofthe corresponding pin 4 which is to be pushed upwards, and then theypush this pin 4 upwards until the shoulder 8 of the pin strikes theunderside of the narrowing wing 9 of the opening S. The pin 4 can now bedetected by touch by a user, the pins 4 of a braille cell which has beenmoved upwards forming a braille symbol. This situation is illustrated inFIG. 4D. By moving the sliding parts back down again, the pins 4 can bemoved back to the low position, with the result that the informationdisplayed by the braille cell 1 is erased.

FIGS. 5 and 6 show the second possible embodiment in which in each pairof leaf springs 10 one leaf spring 10 has to be bent around a wedge inorder to be able to move the corresponding pin 4 upwards, while theother leaf spring 10 has to be moved upwards via the gap 24 in order tob able to move the corresponding pin 4 upwards.

What is claimed is:
 1. A Braille cell comprising; frame, a touch boardand a plurality of touch pins, each touch pin being enclosed in a cavityin the touch board such that each touch pin is displaceable in alongitudinal direction from a low position, in which the touch pin doesnot project above a touch surface of the touch board, to a highposition, in which the touch pin projects above the touch surface of thetouch board by a predetermined length, the frame having arranged thereina pressure-exerting member, the pressure-exerting member being moveableto a predetermined position such that a specific touch pin is movableinto the high position, said pressure-exerting member having a first enddisplaceable, by a first displacement mechanism, in a directionperpendicular to the longitudinal direction such that the first end ofthe pressure-exerting member is moveable between a first position and asecond position, in the first position the pressure-exerting memberbeing configured to prevent placement of the specific touch pin in thehigh position, and in the second position the pressure-exerting memberbeing configured to enable placement of the specific touch pin in thehigh position, and wherein a second displacement mechanism is configuredto displace the first end of the pressure-exerting member, after thefirst end has adopted the second position, in the longitudinaldirection, such that the specific touch pin is placed in the highposition.
 2. The Braille cell of claim 1, wherein the first displacementmechanism comprises a plurality of first displacement members, each ofsaid first displacement members being configured to displace therespective first ends of a plurality of said pressure-exerting members,and wherein a retention member is arranged in the frame proximate toeach touch pin, each said retention member being configured to retainthe first end of one of the pressure-exerting members in said firstposition after the first end is displaced in the longitudinal directionby the second displacement mechanism.
 3. The Braille cell of claim 2,wherein the retention member is a wedge-shaped member tapering from afirst end to a second end along an axis parallel to the longitudinaldirection.
 4. The Braille cell of claim 3, wherein a pair of saidpressure-exerting members have a pair of said retention membersassociated therewith, said retention members being wedge-shaped andformed of different lengths.
 5. The Braille cell of claim 1, whereineach first displacement member has a portion thereof configured to bedisplaceable by one of the group selected from: piezoelectricity andmagnetic forces.
 6. The Braille cell of claim 1, wherein eachpressure-exerting member has a projection configured to interact withone of said first displacement members.
 7. The Braille cell of claim 1,wherein the second displacement member comprises a camshaft.
 8. Adisplay comprising: a touch board having a plurality of groups of touchpins arranged therein, each group of touch pins being configured to forma Braille symbol, each touch pin being displaceable in a longitudinaldirection from a low position, in which the touch pin does not projectabove a touch surface of the touch board, to a high position, in whichthe touch pin projects above the touch surface of the touch board; and apressure-exerting member moveable to a predetermined position such thata specific touch pin is movable into the high position, saidpressure-exerting member having a first end displaceable in a directionperpendicular to the longitudinal direction such that the first end ofthe pressure-exerting member is moveable between a first position and asecond position, in the first position the pressure-exerting memberbeing configured to prevent placement of the specific touch pin in thehigh position, and in the second position the pressure-exerting memberbeing configured to enable placement of the specific touch pin in thehigh position.
 9. The display of claim 8, further comprising means fordisplacing said pressure-exerting member in a direction perpendicular tothe longitudinal direction.
 10. The display of claim 8, furthercomprising means for displacing the first end of the pressure-exertingmember in the longitudinal direction.